Department of Food Science, University of Wisconsin, Madison, Wisconsin 53706, USA.
J Dairy Sci. 2011 Sep;94(9):4264-76. doi: 10.3168/jds.2010-3698.
Three Hofmeister salts (HS; sodium sulfate, sodium thiocyanate, and sodium chloride) were evaluated for their effect on the textural and rheological properties of nonfat cheese. Nonfat cheese, made by direct acidification, were sliced into discs (diameter=50 mm, thickness=2 mm) and incubated with agitation (6 h at 22°C) in 50 mL of a synthetic Cheddar cheese aqueous phase buffer (pH 5.4). The 3 HS were added at 5 concentrations (0.1, 0.25, 0.5, 0.75, and 1.0 M) to the buffer. Post-incubation, cheese slices were air dried and equilibrated in air-tight bags for 18 h at 5°C before analysis. Small amplitude oscillatory rheology properties, including the dynamic moduli and loss tangent, were measured during heating from 5 to 85°C. Hardness was determined by texture profile analysis. Acid-base buffering was performed to observe changes in the indigenous insoluble (colloidal) calcium phosphate (CCP). Moisture content decreased with increasing HS concentration. Cheeses incubated in high concentrations of SCN(-) softened earlier (i.e., loss tangent=1) compared with other HS treatments. Higher melting temperature values were observed for cheeses incubated in high concentrations of SO(4)(2-). Hardness decreased in cheeses incubated in buffers with high concentrations of SCN(-). The indigenous CCP profile of nonfat cheese was not greatly affected by incubation in Cl(-) or SCN(-), whereas buffers with high concentrations of SO(4)(2-) reduced the acid-base buffering contributed by CCP. The use of high concentrations (1.0M) of SCN(-) for incubation of cheeses resulted in a softer protein matrix at high temperatures due to the chaotropic effect of SCN(-), which weakened hydrophobic interactions between CN. Cheese samples incubated in 1.0M SO(4)(2-) buffers exhibited a stiffer protein matrix at high temperatures due to the kosmotropic effect of SO(4)(2-), which helped to strengthen hydrophobic interactions in the proteins during the heating step. This study showed that HS influenced the texture and rheology of nonfat cheese probably by altering the strength of hydrophobic interactions between CN.
三种霍夫迈斯特盐（HS；硫酸钠、硫氰酸钠和氯化钠）被评估其对低脂干酪的质构和流变性质的影响。通过直接酸化制成的低脂干酪被切成圆盘（直径=50mm，厚度=2mm），并在 50mL 合成切达干酪水相缓冲液（pH5.4）中搅拌孵育（22°C 下 6h）。将 3 种 HS 添加到缓冲液中 5 个浓度（0.1、0.25、0.5、0.75 和 1.0M）。孵育后，将奶酪片在 5°C 下空气干燥并在密封袋中平衡 18h，然后进行分析。在从 5°C 加热到 85°C 的过程中，测量小振幅振荡流变性质，包括动态模量和损耗角正切。通过质地分析测定硬度。进行酸碱缓冲作用以观察内源性不溶性（胶体）磷酸钙（CCP）的变化。随着 HS 浓度的增加，水分含量降低。与其他 HS 处理相比，在高浓度 SCN(-)下孵育的奶酪更早软化（即损耗角正切=1）。在高浓度 SO(4)(2-)下孵育的奶酪观察到较高的熔融温度值。在高浓度 SCN(-)下孵育的奶酪硬度降低。CCP 对内源非脂干酪的影响不大。Cl(-)或 SCN(-)孵育对 CCP 的酸碱缓冲作用影响不大，而高浓度 SO(4)(2-)的缓冲液降低了 CCP 的酸碱缓冲作用。由于 SCN(-)的离液效应，在孵育奶酪时使用高浓度（1.0M）的 SCN(-)会导致高温下蛋白质基质变软，这削弱了 CN 之间的疏水相互作用。在 1.0M SO(4)(2-)缓冲液中孵育的奶酪样品在高温下表现出更硬的蛋白质基质，这是由于 SO(4)(2-)的反离子效应有助于在加热过程中加强蛋白质中的疏水相互作用。本研究表明，HS 通过改变 CN 之间的疏水相互作用强度，可能影响低脂干酪的质地和流变性质。
